Geo Dipa Dieng Scaling Mitigation Pilot Plant by Mannvit
Article - 09/09/2022

Scaling mitigation plant, Indonesia

Mannvit is presenting "New Pilot Plant Unit for Optimization of Geothermal Power Process" about a new mobile pilot plant unit that was designed and built for Geo Dipa Energi (GDE) in Indonesia at the Indonesia International Geothermal Convention & Exhibition September 14th-16th. The purpose of the pilot plant was to test different process cycles and find the most effective method of scale mitigation for GDE geothermal power plants. The pilot plant was designed with great flexibility, with two parallel process lines for testing two process options simultaneously.

The development of geothermal power plant is a large investment.  Thorough planning is most important, here including to understand the geothermal resource, to operate drilling campaigns and flow test the wells, but not the least to interpret test results and from there to determine the most feasible power process. Likewise, when planning for extension of an existing geothermal power plant or even just increasing the efficiency of an operating plant, selecting the most suitable method is important. Not only is this important factor to maximize the power output throughout the plant lifetime but as well may this affect the plant availability factor, either in positive or negative way.

The Process

The brine and steam from well being tested is led through intake spool where the intake pressure is controlled and the two-phase flow regulated by a combination of orifice and pressure control valve. For safety of personnel and equipment the flow to the pilot plant is automatically stopped by emergency shut-off valve in case of abnormal operation or failure of power, compressed air, or cooling water supply. The steam is separated from brine in low- and high-pressure separators. The chemicals for mitigation can be accurately dosed into the brine either before separation (two phase) or into separated brine. The brine from the separators is divided into two test lines. One line consists of vaporizer and preheater simulating a brine heated organic Rankine cycle. 

The other line is used for simulating high pressure separation. The steam is condensed and used for diluting of fluid handling chemicals and to dilute the brine for injection tests. The separator pressures and levels are automatically controlled and temperatures and flows in the test lines monitored online. The brine flow in the test lines is controlled by orifices and control valve at the outlet. Holdup vessels can be used for increasing the residence time to simulate the proposed actual conditions in the injection lines of full-size plant. The holdup vessels consist of serially connected vertical pipes with narrow residence time and downward flow to avoid separation of suspended solids. Finally, the suitability of brine for injection can be tested in a packed be filled with rock cuttings.

Photo: Thorsteinn Sigmarsson on site at Dieng's scaling power plant (top). Mannvit's staff work on the installation in Dieng (bottom).